He was re-elected in the 2006 election to the seat of Croydon with a two-party preferred vote of 76 percent. At the 2010 election Atkinson was again re-elected, but with a 15.6 percent swing against him.[7] This was significantly higher than the average swing of 7.8 points against the Labor Party at that election.[8] This is partially attributed to the Gamers 4 Croydon Party, which received 3.7 percent of votes in his seat of Croydon. Following his re-election, he announced he would resign from the Rann ministry but remain on the backbench.[4] Atkinson was re-elected with an increased margin at the 2014 election.

In September 2016, Peter Malinauskas moved house and into Atkinson's electorate of Croydon. He said of Atkinson: "Mick [Atkinson] knows the movements of every single one of his constituents – I suspect I’m no exception.”[9]

Atkinson has blocked attempts to introduce a R18+ for video games in Australia.[10] In a letter on the subject, Atkinson stated, "I don't support the introduction of an R18+ rating for electronic games, chiefly because it will greatly increase the risk of children and vulnerable adults being exposed to damaging images and messages."[11]

He withdrew his support for a discussion paper released for public consultation on the subject of an "R18+" rating.[12][13] Unanimity from Atkinson and his fellow state and federal Attorneys-General is required for the introduction of the rating (or a change to that requirement).[11] Australia's rating system lacked a classification for games above MA15+ at the time.[14] It therefore lacked not only an equivalent rating to the ESRB's AO (adults only) rating but also an equivalent to its Mature (17+) rating.[14]

In 2009, Atkinson, in his role as attorney-general of South Australia, introduced laws into parliament that made internet commentary on the upcoming 2010 election illegal unless the commenter provided their real name and postcode. The laws were passed, and came into effect on 6 January 2010.[15] Following public criticism, Atkinson later promised to repeal the section following the 2010 South Australian election and indicated it would not be enforced during the electoral period.[16]

In 2008, Atkinson introduced legislation aimed at increasing the rights of victims of crime. The legislation purported to allow victims to suggest a suitable sentence for the offender and made it compulsory for judges to consider imposing a restraining order on convicted sex offenders.[17]

Since accepting his role as speaker, Atkinson has used his casting vote in Parliament to oppose several bills presented during the Weatherill government. These include a bill which would have allowed transgender people to have their gender officially changed on their birth certificates[18] and another bill intended to enable voluntary euthanasia. [19]